hot springs in Iceland, like the ..
1. – Life in hot springs – Te Ara Encyclopedia of New Zealand
This artist's animation features Cyanidioschyzon, a spherical green-colored red alga found in acid springs. It uses sunlight for energy, and performs oxygen photosynthesis by processes identical to those in cyanobacteria and plants.
In an effort to study photosynthesis, ..
In microbial biofilms growing on the rock surfaces of anoxic brine pools fed by hot springs containing arsenite and sulfide at high concentrations, we discovered light-dependent oxidation of arsenite [As(III)] to arsenate [As(V)] occurring under anoxic conditions.
photosynthesis - Organisms using thermal energy as …
"Before we found a way to crystallise the cytochrome, we had a general picture of the photosynthetic process, but possessed only a fraction of a percent of the information we now have.
Those in hot springs may get a lot of ..
The microbial mats are fascinating communities that are often fueled by primary CO2 fixation by cyanobacteria. These communities were dominant in the early Earth and helped to establish the oxidizing environment of the planet. We are working on microbial mats in hot springs of Yellowstone National Park, as shown in Figure 1. These mats are about 1 cm thick and the cyanobacteria are in the top ~1 mm. The mat environment is extremely interesting since the cells experience high O2 and light during the day (the mats can be 800% saturation for O2 during the day!!) and go anaerobic during the night. There is a strong metabolic switching from respiration and photosynthesis during the day to fermentation metabolism and N2 fixation during the night. Recently, we worked hard to develop molecular tools and procedures to explore the physiology of the mats with sophisticated in situ experimentation (; ), and to generate axenic strains of some of the organisms ). In initial studies, we worked with people at TIGR to have two cyanobacterial genomes sequenced (from organisms that grow at 50-65°C) and found that the genomes appeared to be fluid (while the orthologues between the genomes were pretty similar, there was a complete lack of synteny; the two genomes were scrambled with respect to gene arrangement relative to each other) (). Furthermore, we discovered that these high temperature cyanobacteria were capable of N2 fixation (), which was extremely surprising since others had suggested that these unicellular cyanobacteria (Synechococcus strains) that grow at the higher temperatures could not fix N2. We then measured levels of transcripts encoding the nitrogenase protein subunits (NifD) and N2 fixation in the mat over the diel cycle. While the nitrogenase transcripts and Nif proteins accumulate in the evening, as the mat becomes anoxic, the majority of the N2 fixation occurs in the morning when the mats are still anoxic, but now there is much more energy, generated from both photosynthetic electron flow and some respiration; this allows for high level N2 fixation. In other words, the cells were in a low energy state during the night (they could only do fermentation metabolism at that time), and since the nitrogenase requires a high energy input (16 ATP for the conversion of N2 to ammonium), the fixation of N2 during the evening is low. When more energy becomes available in the morning, and since the cells already have the N2 fixation machinery in place, they can fix high levels of N2. When O2 begins to accumulate in the mats as the light intensity increases, the nitrogenase activity is inhibited (the nitrogenase is O2 sensitive) and ultimately the enzyme appears to turn over (and is remade the next evening) (). Figure 2 depicts the level of nitrogen fixation over the diel cycle, and the conditions associated with different times of the day.